I had something similar with a Magnavox CRT TV years ago. It would "helpfully" show on the screen "STEREO" or "MONO". Every time the signal lost the stereo si

I had something similar with a Magnavox CRT TV years ago. It would "helpfully" show on the screen "STEREO" or "MONO". Every time the signal lost the stereo signal, it would flash MONO, then a couple seconds later flash STEREO. Was a real problem on some channels that a slightly weak audio signal.